1. Technical Field
The present invention relates to a composite article having improved heat conductivity and wear resistance, and more particularly to an improved heat conductive and wear resistant chill plate for continuous casting of metals. The present invention will be particularly described with respect to continuous casting of ferrous metals, such as iron and steel.
2. Description of the Prior Art
U.S. Pat. No. 4,197,902 discloses electrolytic deposition of a layer of nickel combined with alumina or silicon carbide filler particles onto a copper or copper alloy mold, for use in continuous casting. The layer is said to provide wear resistance and thermal shock resistance and to adhere well to the copper base. It is indicated in the patent that application of a coating by flame spraying or plasma spraying can not be used for making a continuous casting mold because coatings applied by flame or plasma spraying tend to be porous and thus relatively corrosion prone. Also, it is indicated in the patent that coatings applied by flame or plasma spraying have relatively low adherence and shock resistance. It is also indicated that such coatings have a non-uniform thickness which requires subsequent machining of the coatings making flame or plasma spraying uneconomical. A plasma sprayed molybdenum coating was mentioned as an example.
U.S. Pat. No. 4,693,296 discloses the construction of a break ring in a continuous caster by first plasma spraying boron nitride, silicon nitride, or aluminum nitride into a mold. A second layer of zirconium oxide, aluminum oxide, or silicon carbide is then applied by plasma spraying, followed by plasma spraying a third layer of copper or aluminum oxide. The mold is shaped so that the first layer of boron nitride, silicon nitride, or aluminum nitride constitutes the wear surface of the break ring.
Prior U.S. Pat. No. 3,892,644 discloses a cermet powder which comprises a homogeneous blend of a refractory material and a matrix material. A suitable matrix material is said to be copper. Suitable refractory materials listed include silicon carbide and tungsten carbide. One example of a cermet powder given in the patent is a blend of boron carbide and copper. The patent is directed primarily to the process by which the homogeneous blend is made. It is suggested in the patent that the cermet particles are useful for cutting tools and wear parts.